The invention relates to a weaving machine and a method for three-dimensional weaving. Woven fabrics are a frequently used as reinforcing means in composite materials. In doing so, the fabric fibers are preferably subject to tensile loading. Referring to three-dimensionally formed components such as occur in automobile or ship body construction, the fabric incorporated in the composite material must be adapted to the desired component form.
This may be accomplished, for example, in that the whole fabric is cut into individual pieces that are then arranged so as to overlap on the three-dimensional component and are then incorporated by lamination. This process is time-consuming and expensive. Therefore, it has also been suggested to drape the two-dimensional fabric, in which case, however, stretched regions are formed and the fabric density in the stretched regions is reduced. Optionally, excess material must even be cut off or superimposed in pleats.
Mechanized methods and devices for the manufacture of three-dimensional fabrics have also been described.
From publication DE 41 37 082 C2 it has been known to provide a reed with reed lamellae that are arranged in casting-on direction and in weft thread direction in a manner that they can be shifted relative to each other. The warp threads are guided over the reed lamellae and their distance is adjusted so that a spatial contour can be obtained. A similar arrangement is also described in U.S. Pat. No. 5,465,762. The resultant contour changes the structure from a planar, two-dimensional form to a three-dimensional form during the abutment of the lamella. Such a weaving process is relatively slow. Frequently, it is necessary that the change into the three-dimensional form be supported by additional draping.
The author of publication EP 0 302 012 B1 suggests that a three-dimensional fabric form be produced by spherically shaped draw-off rollers. In doing so, the fabric is stretched after the weaving operation in order to achieve the desired form.
Considering the method known from EP 0 819 188 B1, a three-dimensionally formed fabric zone is formed in that the number of woven-in warp threads or weft threads varies, or that the type of weave is changed. The distance of the warp threads is achieved by changing the distance of the reed lamellae. The reed is fan-shaped, so that the distance between two adjacent reed lamellae varies. Therefore, by shifting the reed, the distance between two adjacent warp threads can be adjusted. The contour change is created by the reed during casting-on of the warp thread.
Publication DE 39 15 085 C2 describes a device for the manufacture of a three-dimensional fabric, wherein, between the shed-forming device and the drawing-off of the fabric a molded element is arranged upstream of the fabric edge, said molded element having the shape of the fabric form that is to be produced. The molded element may be made of several disks or, alternatively, of a series of adjustable tappets. Also in the case of this method, the desired form is created during the casting-on of the weft thread.
The object to be achieved by the invention may be viewed as the provision of a weaving machine, as well as a weaving method, that improve the until now known methods and devices for the manufacture of three-dimensional fabrics.